Heat Pump Guide: Types, Sizing and Maintenance

Understanding Heat Pumps

Heat pumps are the most energy-efficient heating technology available for homes. They extract renewable heat from the environment and deliver it to your home at 2.5-4 times the efficiency of any combustion-based heating system. This guide covers everything you need to know before investing in a heat pump.

Air Source vs Ground Source

For the vast majority of homeowners, an air source heat pump is the right choice. The lower cost, simpler installation, and minimal garden disruption make it practical for both new builds and retrofits. Ground source is worth considering only if you have significant outdoor space and want maximum long-term efficiency.

How Heat Pumps Work

Every heat pump contains the same four core components:

1. Evaporator - Absorbs heat from the air or ground into a refrigerant fluid, which evaporates at very low temperatures (as low as -25C)
2. Compressor - Compresses the refrigerant gas, raising its temperature from 5-10C to 55-75C (this is where the electricity is consumed)
3. Condenser - Transfers the heat from the hot refrigerant to your heating water circuit
4. Expansion valve - Reduces the refrigerant pressure, cooling it back down to restart the cycle

The key insight is that the compressor does not create heat. It concentrates heat that already exists in the environment. Even at 0C, outdoor air contains significant thermal energy. The compressor simply moves this energy from a cold source (outside) to a warm destination (your home).

Maintenance Schedule

Keep the area around the outdoor unit clear of leaves, snow, and debris. Ensure at least 300mm clearance on all sides for airflow. In winter, check that the defrost cycle is working correctly (brief periods of steam from the outdoor unit are normal).

Common Myths Debunked

Myth: Heat pumps do not work below freezing. Reality: Modern ASHPs operate efficiently down to -15C to -20C. In Norway, where winter temperatures regularly reach -20C, heat pumps are the most popular heating system, installed in over 60% of homes.

Myth: Heat pumps are too noisy for residential areas. Reality: At 40-55 dB, a modern ASHP is quieter than a normal conversation (60 dB). Noise regulations require installation at least 1 metre from boundaries and below 42 dB at the nearest neighbour's window.

Myth: You need underfloor heating for a heat pump. Reality: Heat pumps work with radiators, but you may need to upsize some radiators by 1-2 sizes because heat pumps produce water at 35-55C compared to a boiler's 60-80C. Many homes only need 2-3 radiators replaced, not the entire system.

Myth: Heat pumps are too expensive without grants. Reality: Even without grants, a heat pump saving EUR 300-500/year vs oil heating pays back in 12-18 years, with 5-10 years of additional free heating. With grants, payback drops to 5-10 years. Use our heat pump calculator to see your specific payback period.

Myth: Heat pumps use too much electricity. Reality: A well-sized heat pump for a 100 sqm home uses 5,000-7,500 kWh of electricity per year, producing 14,000-21,000 kWh of heat. This adds EUR 1,000-1,800 to your electricity bill but eliminates your entire gas or oil bill. Pairing with solar panels can offset 30-50% of this electricity consumption.